This is a 2000 Passat with engine code ATW.
On he first start of the day the engine cranks and tries to catch.
Eventually I found that if I hold the pedal to the floor it will start.
Once running the idle is very rough.
Anything above Idle the engine is smooth. The car runs great down the road great, lots of power but when at a red light the engine wants to stall. The rpms go so low that the brake booster loses vacuum and the pedal gets hard to push.
The only codes are random/multiple cylinder misfire detected.
If I clear the codes and drive the car the CEL never comes on but if the car idles for some time the CEL will light
I have checked for leaks on the intake, and leaks on the exhaust.
I have replaced with new parts the 1st O2 sensor, mass air flow sensor, timing belt, cam chain tensioner, turbo by-pass valve.
I have replaced with used parts the throttle body and the ECU and performed the throttle body adaptation.
After all the parts that have been replaced, the hard starting and rough idle are still there.